Fosaprepitant is a P/neurokinin-1 (NK1) receptor antagonist and is a prodrug of Aprepitant. The meglumine salt of Fosaprepitant, Fosaprepitant dimeglumine, is approved in the U.S as Emend® in the form of a lyophilized powder for intravenous infusion. Fosaprepitant dimeglumine is rapidly converted to Aprepitant in vivo. It is chemically described as 1-deoxy-1-(methylamino)-D-glucitol[3-[[(2R,3S)-2-[(1R)-1-[3,5-bis(trifluoromethyl)phenyl]ethoxy]-3-(4-fluorophenyl)-4-morpholinyl]methyl]-2,5-dihydro-5-oxo-1H-1,2,4-triazol-1-yl]phosphonate (2:1) having an empirical formula C23H22F7N4O6P.2(C7H17NO5). The structure is depicted below:

Emend® is indicated in adults for use in combination with other antiemetic agents for the prevention of acute and delayed nausea and vomiting associated with initial and repeat courses of highly emetogenic cancer chemotherapy including high-dose cisplatin.
U.S. Pat. No. 5,691,336 to Dorn et al, discloses the compound Fosaprepitant and further describes methods of synthesizing the said compound. U.S. Pat. No. 5,716,942 also to Dorn et al., discloses the use of neurokinin 1 receptor antagonist such as Fosaprepitant for the treatment of inflammatory diseases, pain or migraine, asthma, emesis and nausea.
U.S patent application No. 2007/265329 to Devang et al., discloses subcutaneous pharmaceutical injectable composition comprising a semi-solid delivery vehicle and a pharmaceutically acceptable liquid vehicle, for the sustained release of a 5-HT3 receptor antagonist in the treatment of chemotherapy-induced nausea and vomiting.
U.S. Pat. No. 5,538,982 to Hagan et al., discloses a NK, receptor antagonist for the treatment of emesis and further discloses neurokinin 1 receptor antagonist in combination with anti-inflammatory corticosteroid or a 5HT3 antagonist.
Fosaprepitant dimeglumine easily degrades to Aprepitant unless stored at low temperature. Therefore it is conventionally supplied as a lyophilized formulation to reduce the formation of impurities and to improve the stability of the final formulation.
This invention is directed to stable liquid parenteral formulations of Fosaprepitant that do not need reconstitution before administration.